This project is a continuation of an investigation into the regulation of intermediary metabolism in the kidney by acid-base homeostasis. In previous studies we have related two physiologic processes, the chronic increase in NH4 ion excretion and glutamine utilization in metabolic acidosis and the acute increase in citrate clearance in metabolic alkalosis, to chronic and acute effects of acid-base changes on glutamine and citrate metabolism by tissue slices and mitochondria from renal cortex. Recently we have shown that acid-base balance exerts its effects on renal metabolism by influencing the rate of transport of citrate and glutamine across the inner mitochrondrial membrane. In the proposed research these observations will be extended in order to obtain definitive information on the properties of these transport systems and on the effects of acid-base changes on them. Special emphasis will be given to elucidating the events involved in control of renal ammoniagenesis by comparing metabolism and transport in mitochrondria from renal cortex of chronically acidotic and alkalotic dogs.